Harnessing tailored disorder for broadband light scattering enables high-resolution signal analysis in nanophotonic spectrometers with a small device footprint. Multiple scattering events in the disordered medium enhance the effective path length which leads to increased resolution. Here we demonstrate an on-chip random spectrometer cointegrated with superconducting single-photon detectors suitable for photon-scarce environments. We combine an efficient broadband fiber-to-chip coupling approach with a random scattering area and broadband transparent silicon nitride waveguides to operate the spectrometer in a diffusive regime. Superconducting nanowire single-photon detectors at each output waveguide are used to perform spectral-to-spatial mapping via the transmission matrix at the system, allowing us to reconstruct a given probe signal. We show operation over a wide spectral range with sensitivity down to powers of -111.5 dBm in the telecom band.Two-dimensional (2D) lead halide perovskites with better chemical stability and tunable dimensionality offer new opportunities to design optoelectronic devices. https://www.selleckchem.com/products/tasquinimod.html We have probed the transient absorption behavior of 2D lead halide (bromide and iodide) perovskites of different dimensionality, prepared by varying the ratio of methylammoniumphenylethylammonium cation. With decreasing dimensionality (n = ∞ → 1), we observe a blue shift in transient absorption bleach in agreement with the trend observed with the shift in the excitonic peak. The lifetime of the charge carriers decreased with decreasing layer thickness. The dependence of charge carrier lifetime on the 2D layers as well as the halide ion composition shows the dominance of excitonic binding energy on the charge carrier recombination in 2D perovskites. The excited-state behavior of 2D perovskites discussed in this study shows the need to modulate the layer dimensionality to obtain desired optoelectronic properties.We record nanoscale chemical images of thiobenzonitrile (TBN)-functionalized plasmonic gold nanocubes via tip-enhanced Raman spectroscopy (TERS). The spatially averaged optical response is dominated by conventional (dipolar) TERS scattering from TBN but also contains weaker spectral signatures in the 1225-1500 cm-1 region. The weak optical signatures dominate several of the recorded single-pixel TERS spectra. We can uniquely assign these Raman-forbidden transitions to multipolar Raman scattering, which implicates spatially varying enhanced electric field gradients at plasmonic tip-sample nanojunctions. Specifically, we can assign observations of tip-enhanced electric dipole-magnetic dipole as well as electric dipole-electric quadrupole driven transitions. Multipolar Raman scattering and local optical field gradients both need to be understood and accounted for in the interpretation of TERS spectral images, particularly in ongoing quests aimed at chemical reaction mapping via TERS.Lipophilic dyes such as laurdan and prodan are widely used in membrane biology due to a strong bathochromic shift in emission that reports the structural parameters of the membrane such as area per molecule. Disentangling of the factors which control the spectral shift is complicated by the stabilization of a charge-transfer-like excitation of the dye in polar environments. Predicting the emission therefore requires modeling both the relaxation of the environment and the corresponding evolution of the excited state. Here, an approach is presented in which (i) the local environment is sampled by a classical molecular dynamics (MD) simulation of the dye and solvent, (ii) the electronically excited state of prodan upon light absorption is predicted by numerical quantum mechanics (QM), (iii) the iterative relaxation of the environment around the excited dye by MD coupled with the evolution of the excited state is performed, and (iv) the emission properties are predicted by QM. The QM steps are computed using the many-body Green's function in the GW approximation and the Bethe-Salpeter equation with the environment modeled as fixed point charges, sampled in the MD simulation steps. The comparison to ultrafast time-resolved transient absorption measurements demonstrates that the iterative molecular mechanics (MM)/QM approach agrees quantitatively with both the polarity-dependent shift in emission and the time scale over which the charge transfer state is stabilized. Together the simulations and experimental measurements suggest that the evolution into the charge transfer state is slower in amphiphilic solvents.Doping is able to create novel optoelectronic properties of halide perovskites, and the involved mechanism of efficient emission is still a challenge. Herein Mn2+ substitution into 2D layered perovskites (C8H20N2)PbBr4 was investigated, demonstrating broad-band orange-red emission originating from the 4T1 → 6A1 transition of Mn2+ dopant. The photoluminescence quantum yield (PLQY) of Mn2+ emission is up to 60.8% related to the energy transfer in coupled states. We verify that an actual Mn2+ dopant as low as 0.476% reaches a high PLQY, whereas the nominal adding amount is 0.8 as the Mn2+/Pb2+ ratio. The small activation energy (?6.72 meV) between the Mn2+ d state and the trap state accounts for this highly efficient energy transfer and photoluminescence. The proposed luminescence mechanism in Mn2+-doped 2D halide perovskites would provide unique insights into the doping design toward high-performance luminescence materials.Spectral analysis using chemometrics is extensively used for quantitative chemical analysis in a mixture, but it works powerfully only when the peak intensity is solely proportional to the quantity of chemical components. In this sense, thin films on a solid substrate are not suitable for chemometric analysis, because the molecular orientation also influences the peak intensity via the surface selection rules. In the present study, this long-term analytical issue has readily been overcome by using p-polarized multiple-angle incidence resolution spectrometry (pMAIRS), which has a characteristic that the in-plane (IP) and out-of-plane (OP) vibrational spectra of a thin-film sample are obtained simultaneously in a common ordinate scale. Thanks to this unique power of pMAIRS, the average of the IP and OP spectra annihilates optical anisotropy, yielding an orientation-free spectrum, which enables us to perform the simultaneous quantitative analysis of both quantity change and molecular orientation of the constituents in a thin film.